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Description of problem: Some WebM videos in YouTube are jerky. The following video is an example: http://www.youtube.com/watch?v=7rljVIVHT6o If I download the video with youtube-dl and play it with totem, it is not jerky. I have also seen some other WebM videos in YouTube which are not jerky. Version-Release number of selected component (if applicable): firefox-8.0-3.fc16.x86_64 How reproducible: Happens every time. Steps to Reproduce: 1. Start Firefox. 2. Go to http://www.youtube.com/watch?v=7rljVIVHT6o 3. Play video. Actual results: The video is jerky. Expected results: The video should be smooth. Additional info: The audio is OK.
I forgot to mention that you have to join YouTube's HTML5 trial to test this. This can be done by clicking the link at http://youtube.com/html5
I tested two other computers last weekend. One is running F15/Gnome3/IntelGPU and the other is running F16/XFCE/RadeonX1650. In both cases, the frame rate was better than on my office computer. My office computer is running F16/Gnome3/RadeonHD2400XT. All of these computers have Firefox 8.0.
If I play the webm video that I downloaded with youtube-dl in Firefox with a URL like the following: file:///var/tmp/7rljVIVHT6o.webm then the performance is much better. So the problem seems to have to do with YouTube's HTML5 player.
I can reproduce it too. I escalated it to upstream: https://bugzilla.mozilla.org/show_bug.cgi?id=740342
This bug seems similar to https://bugs.freedesktop.org/show_bug.cgi?id=47776.